1. Field of the Invention
The present invention is directed to aluminum receptacles and, more particularly, to aluminum receptacles having a threaded neck for receiving a cap.
2. Description of the Background
It is known in the art to form drawn, or drawn and ironed, cans from aluminum and steel for use in the packaging of beer, soft drinks, oil, and other liquids. Most metal cans for beer and beverages are adapted to be closed with relatively flat lids or ends which are secured on the cans by double seaming or a similar process. The lids may have tear strips formed in them and pull tabs attached to the tear strips to facilitate access to the tear strips to thereby provide an opening in the lid.
Not all aluminum containers have flat tops. It is known in the art to use a series of necking dies on an aluminum container to form a neck on one end of the container. Threads may then be formed in the neck portion of the container by positioning first and second thread rolling tools adjacent to inside and outside surfaces, respectively, of the neck and rotatably moving the tools against the surface. Threaded aluminum containers have typically been made from relatively thick metal, i.e., at least 0.020 inches thick. The material is typically pure aluminum (99.5-99.8% aluminum) which is relatively soft and permits the forming of threads in the neck.
The insides of aluminum containers are very often provided with a coating which prevents interaction between the raw aluminum and the contents of the container. The process of forming threads on the neck portion of the container may crack and/or dislodge portions of the coating thereby allowing the contents of the container to come into contact with raw aluminum. Furthermore, a coating which is cracked or otherwise damaged may work loose after the container is filled thereby contaminating the contents of the container.
An improvement over forming the threads directly in the aluminum container is to secure a sleeve of plastic or other material around the neck of the aluminum container. Examples of the use of such a sleeve can be found in U.S. Pat. Nos. 5,713,235 entitled xe2x80x9cMethod and Apparatus for Die Necking a Metal Container,xe2x80x9d 6,010,026 entitled xe2x80x9cAssembly of Aluminum Can and Threaded Sleeve,xe2x80x9d 5,718,352 entitled xe2x80x9cThreaded Aluminum Cans and Methods of Manufacture,xe2x80x9d 5,778,723 entitled xe2x80x9cMethod and Apparatus for Necking a Metal Container and Resultant Container,xe2x80x9d 6,010,028 entitled xe2x80x9cLightweight Reclosable Can with Attached Threaded Pour Spout and Methods of Manufacture,xe2x80x9d and 5,822,843 entitled xe2x80x9cMethod of Making Bottle-Shaped Metal Cans.xe2x80x9d Very often, to prevent rotation of the sleeve on the container, small dents, ribs, slots or the like are provided on the container and/or the sleeve. The sleeve can also be adhesively bonded to the container to prevent relative rotation. However, forming of dents, ribs, slots, or the like in the container may damage the protective coating on the inside of the container. Therefore, the need exits for a method for securing a threaded sleeve to the neck of an aluminum container and the improved container resulting therefrom.
The present invention is directed to an aluminum container comprising a base portion, a substantially vertical wall portion extending upwardly from the base portion, a transition portion extending from the wall portion, and a neck portion extending from the transition portion. The neck portion is tapered and has an upper end having a wall thickness that is preferably less than the thickness of the wall of the remainder of the neck portion. The upper end of the neck portion may also be chamfered.
The aluminum container of the present invention may be combined with a threaded sleeve to form a receptacle. The sleeve has an outer surface and an inner surface. The outer surface has threads thereon and the inner surface has a taper complementary to the taper of the neck portion so as to form a friction fit with the neck portion. The sleeve may also have a notch formed in the periphery of its upper outside surface. When the upper chamfered end of the neck is curled, the neck portion extends over a top end portion of the sleeve and terminates in the notch in the sleeve.
The present invention is also directed to a method of affixing a sleeve to the neck of an aluminum bottle of the type having a tapered neck and wherein the sleeve has a complementary taper. The method is comprised of positioning the sleeve onto the neck such that a portion of the neck extends beyond the sleeve, and curling the portion of the neck extending beyond the sleeve so that the curl covers at least a portion of the upper end of the sleeve. The curling step causes the sleeve to seat on the neck so as to form a friction fit therewith.
By providing the neck portion of the container with a taper, and providing the threaded sleeve with a complementary taper, a friction fit can be obtained without requiring any dimples, dents, or similar structure in either the neck portion or the threaded sleeve. Because of the taper, the threaded sleeve can be easily inserted onto the neck portion of the container. Thereafter, the curling process (which curls the end of the neck portion extending beyond the sleeve) pushes the threaded sleeve further down onto the neck portion of the container thereby causing an extremely tight friction fit. By controlling the amount of the neck portion which extends beyond the threaded sleeve, and therefore the amount of material available for curling, the threaded sleeve can be precisely positioned on the neck portion of the container. Additionally, by providing a notch in the upper outside peripheral surface of the threaded sleeve, the curled edge of the neck portion may terminate in the notch thereby covering the entire top edge of the threaded sleeve as well as providing a smooth profile for the finished receptacle. There is no exposed aluminum, and no possibility of damaging the protective coating on the inside of the container. Those, and other advantages and benefits, will become apparent from the detailed description of the preferred embodiments hereinbelow.